Prior art fuel injector designs exhibited reduced fuel flow over use due to hydrocarbon deposits accumulating on the tip of the injector. Testing has shown that, prior to cleaning (0 to 150 million cycles), a general decreasing trend in fuel flow in twelve test injectors is exhibited as each injector accumulates additional cycles. At 75 million cycles and 150 million cycles, static flow tests were conducted to determine the fuel flow rate through the injectors. At 75 million cycles, flow rate decreased as much as 4.5% from baseline measurements. At 150 million cycles, flow rate decreased as much as 7.5% from baseline. Flow rates between 0 and 75 million cycles, and flow rates between 75 million and 150 million cycles were interpolated. At 150 million cycles, the fuel injectors were removed, cleaned, and reinstalled. Static flow tests were conducted on the cleaned injectors to determine fuel flow rate. Fuel flow through the cleaned injectors was restored to its original value.
It would be beneficial to develop a fuel injector in which deposits, which decrease fuel flow through the injector, are prevented from forming.
Briefly, the present invention provides a valve seat for a fuel injector. The valve seat comprises a longitudinal axis extending therethrough and a channel extending along the longitudinal axis. The channel has a channel wall. The valve seat also comprises a needle contact area upstream from the channel. The needle contact area is proximate to the channel such that fuel deposits form exclusively on the channel wall and on the valve seat upstream of the needle contact area.
Additionally, the present invention discloses a needle for a fuel injector. The needle comprises a generally tubular perimeter and a longitudinal axis extending therethrough. The needle also comprises a downstream end and a generally circular recess in the downstream end. The generally circular recess has a center generally along the longitudinal axis and an outer recess perimeter. The outer recess perimeter is proximate to the generally tubular perimeter such that fuel deposits form exclusively in the generally circular recess.
Additionally, the present invention discloses a fuel injector. The fuel injector comprises a longitudinal axis extending therethrough, a valve seat, and a needle. The valve seat comprises a channel extending along the longitudinal axis and a needle contact area upstream from the channel. The channel has a channel wall and the needle contact area is proximate to the channel such that fuel deposits form exclusively on the channel wall and on the valve seat upstream of the needle contact area. The needle comprises a generally tubular perimeter, a downstream end, and a generally circular recess in the downstream end. The generally circular recess has a center generally along the longitudinal axis and an outer recess perimeter. The outer recess perimeter is proximate to the generally tubular perimeter such that fuel deposits form exclusively in the generally circular recess.
Further, the present invention discloses a method of forming deposits on a valve seat of a fuel injector exclusively in a fuel channel and upstream from a needle contact area and on a needle of the fuel injector exclusively in a recess in a downstream end of the needle. The method comprises the steps of providing an injector including a longitudinal axis extending therethrough, a valve seat, and a needle. The valve seat comprises a channel extending along the longitudinal axis and a needle contact area upstream from the channel. The channel has a channel wall. The needle contact area is proximate to the channel such that fuel deposits form exclusively on the channel wall and on the valve seat upstream of the needle contact area. The needle includes a generally tubular perimeter; a downstream end, and a generally circular recess in the downstream end. The generally circular recess has a center generally along the longitudinal axis and an outer recess perimeter. The outer recess perimeter is proximate to the generally tubular perimeter such that fuel deposits form exclusively in the generally circular recess. The method also includes operating the fuel injector.